Traffic congestion is an increasing problem as the world's urban population increases, while the roadway resources remain limited. It is currently characterized by slower speeds, longer trip times, and increased vehicular queuing. The most common example is the physical use of roads by vehicles. Additionally, traffic may be very congested at certain times of the day and not at other times. However, proposals to alleviate traffic congestions have had issues because of the difficulty in predicting traffic congestions.